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<p><strong><code>Number.EPSILON</code></strong> 属性表示 1 与<a href="Reference/Global_Objects/Number" title="JavaScript 的 Number 对象是经过封装的能让你处理数字值的对象。Number 对象由 Number() 构造器创建。"><code>Number</code></a>可表示的大于 1 的最小的浮点数之间的差值。</p>
<p>你不必创建一个 <a href="Reference/Global_Objects/Number" title="JavaScript 的 Number 对象是经过封装的能让你处理数字值的对象。Number 对象由 Number() 构造器创建。"><code>Number</code></a> 对象来访问这个静态属性（直接使用 <code>Number.EPSILON</code>）。</p>
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<th class="header" colspan="2"><code>Number.EPSILON</code> 属性的属性特性：</th>
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<td>writable</td>
<td>false</td>
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<td>enumerable</td>
<td>false</td>
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<td>configurable</td>
<td>false</td>
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<h2 id="描述">描述</h2>
<p><code>EPSILON</code> 属性的值接近于 <code>2.2204460492503130808472633361816E-16</code>，或者 <code>2<sup>-52。</sup></code></p>
<h2 id="示例">示例</h2>
<h3 id="测试是否相等">测试是否相等</h3>
<pre><code  class="language-javascript">x = 0.2;
y = 0.3;
z = 0.1;
equal = (Math.abs(x - y + z) &lt; Number.EPSILON);
</code></pre>
<h2 id="规范">规范</h2>
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<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-number.epsilon" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Number.EPSILON</small></a></td>
<td><span class="spec-Standard">Standard</span></td>
<td>最初定义</td>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-number.epsilon" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Number.EPSILON</small></a></td>
<td><span class="spec-Draft">Draft</span></td>
<td> </td>
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<h2 id="浏览器兼容性">浏览器兼容性</h2>
<div><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
            This compatibility table still uses the old format,
            because we haven't yet converted the data it contains.
            <strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<li class="selected"><a>Desktop</a></li>
<li><a>Mobile</a></li>
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<th>Feature</th>
<th>Chrome</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari</th>
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<td>Basic support</td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td><a href="/en-US/Firefox/Releases/25" title="Released on 2013-10-29.">25.0</a> (25.0)</td>
<td><span style="color: #f00;">未实现</span></td>
<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
<td>9</td>
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<th>Feature</th>
<th>Android</th>
<th>Chrome for Android</th>
<th>Firefox Mobile (Gecko)</th>
<th>IE Mobile</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
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<td>Basic support</td>
<td><span style="color: #f00;">未实现</span></td>
<td><span style="color: #f00;">未实现</span></td>
<td>25.0 (25.0)</td>
<td><span style="color: #f00;">未实现</span></td>
<td><span style="color: #f00;">未实现</span></td>
<td>9</td>
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<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="Reference/Global_Objects/Number" title="JavaScript 的 Number 对象是经过封装的能让你处理数字值的对象。Number 对象由 Number() 构造器创建。"><code>Number</code></a></li>
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